The field of the present invention is valve actuating systems for the valves of an internal combustion engine particularly employing multiple intake or exhaust valves.
With modern internal combustion engines, multiple valves for each of the intake and exhaust systems have been employed as a means for improving engine efficiency. Additionally, it is often found that the contour of the combustion chamber head is such that the valves are inclined relative to one another if the valve stem is to be aligned with the local normal of the surface. Under such conditions, the mechanisms necessary for actuating the valves can become very complicated. Two prior art devices illustrating substantial complication in valve actuating structure are shown in FIGS. 4 and 5. In FIG. 4, a pair of valves 10 are illustrated as being driven by secondary rocker arms 12 which are pivotally mounted to two shafts 14. The shafts 14 extend outwardly from the location of the valve 10 as can best be seen in the Figure. The secondary rocker arms 12 are in turn driven by primary rocker arms 16 which are in turn driven by camshafts 18. This system suffers from undue complication because of the multiple shafts 14 and the multiple camshafts 18. Additionally, the extension of the shafts 14 outwardly from the valves requires substantial room adding significantly to the overall profile of the head structure.
In the prior art illustration of FIG. 5, an improved arrangement is illustrated. Two valves 20 are driven by secondary rocker arms 22. The secondary rocker arms 22 are in turn associated with primary rocker arms 24 driven by a camshaft 26. Through the location of the second rocker arms 22 between the valves 20 as can best be seen in FIG. 5, a single camshaft 26 may be employed. However, the extension of these rocker arms 22 inwardly between the valves 20 generally necessitates a compromise in valve angle and/or in head width so as to accommodate the appropriate mechanism. Additionally, two shafts (not shown) are required for the secondary rocker arms 22. Lastly, the compromise necessary for appropriate valve orientation limits the length of the secondary rocker arms 22. Thus, substantial complexity and a compromise in design have generally been required of multiple valve systems with mutually inclined valves.